Metastasis is the spread of a disease from one organ or part to another non-adjacent organ or part. It is commonly associated with cancer, where cancer cells migrate from the place where the cancer started (the “primary tumor”) to other parts parts of the body to form a new tumor. The new tumor is a “metastic” or “secondary” tumor of the primary tumor. Thus, if breast cancer cells metastasize to the lungs, the secondary tumor is called metastatic breast cancer, not lung cancer. Most tumors and other neoplasms can metastasize; thus, the clinical management of metastasis is of great importance.
An extraordinarily complex process, metastasis consists of a series of important steps. These steps include detachment of tumor cells from the primary tumor, invasion through surrounding tissues and basement membranes, entry and survival in the circulation, lymphatic system or peritoneal space, and establishment and proliferation of the tumor cells in a distant target organ. The specific molecular mechanisms behind these steps remain unclear, thus, identifying effective methods to prevent or suppress tumor metastasis has been challenging. New methods are needed.